What is happening with migrant children at the southern US border?

The US is bracing for a 20-year high in numbers of migrants arriving at the southern border, including thousands of children who are being kept in government-run detention facilities that critics say are inhumane.

A pandemic health order means that most adults and families are being summarily turned away, but the Biden administration has allowed unaccompanied children under the age of 18 to enter the US while their claims are processed.

The record-breaking influx of children being held in these camps has led US officials to send in the Federal...